Holland America Line’s Eurodam. Thomas DePrince purchased a $235,000 20.64 carat diamond on the ship knowing it was worth millions. He sued the retailer when it terminated his order, but a Miami-Dade trial court ruled in favor of the retailer because DePrince, a retired antiques and jewelry dealer, knew the diamond’s true value. Andy Newman

Holland America Line’s Eurodam. Thomas DePrince purchased a $235,000 20.64 carat diamond on the ship knowing it was worth millions. He sued the retailer when it terminated his order, but a Miami-Dade trial court ruled in favor of the retailer because DePrince, a retired antiques and jewelry dealer, knew the diamond’s true value. Andy Newman

No deal for gem-savvy passenger on shipboard diamond

A cruise ship passenger who tried to get away with a too-good-to-be-true diamond deal won’t be able to cash in for the seller’s mistake, a Miami-Dade trial court ruled Thursday.

In 2013, Thomas DePrince stumbled across a 20.64 carat emerald-cut diamond aboard Holland America Line’s Eurodam priced at $235,000. He quickly purchased the stone, knowing it was really worth millions, according to the court.

When the retail operator, Starboard Cruise Services, realized the price tag reflected the per carat cost, not the total cost, the company called DePrince and explained the mistake. The retailer canceled the sale and refunded the purchase price to DePrince’s credit card.

$4.8 millionTrue cost of the 20.64 carat emerald-cut diamond

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DePrince then filed a lawsuit in Miami-Dade Circuit Court in 2013, allegeing a breach of contract, but a Miami-Dade judge sided with Starboard and threw out the case. An appeals panel disagreed, sending the case back to trial court.

On Thursday, the court agreed with the original verdict, ruling in favor of Starboard.

In an opinion written by Judge Michael Hanzman, the court said that DePrince had “significant experience in buying and selling fine jewlery.” In fact, he had consulted his life partner and his sister, both certified gemologists, before the purchase.

His sister, Carolyn, told DePrince that the diamond was likely “worth millions,” but DePrince went ahead with the purchase. (The actual value of the diamond was $4.8 million, 20 times the price DePrince paid.)

The diamond was never delivered to DePrince’s home in New York.

“Starboard Cruise Services is very pleased that the jury agreed with the trial judge’s original decision that the plaintiff’s claim has no merrit,” said Eric Isicoff, the attorney who represented Starboard.